If you've checked in on the blog of the San Francisco transit-app company Uber over the past couple of months, the latest post might have read, "Uber Secretos están llegando!" or " Psst! Du kan följa bildflödet #ubersnaps live här."

Uber, which connects smart-phone users with private drivers of sedans, SUVs, and taxis, is no longer just a scrappy Silicon Valley start-up burning through its venture capital funding. Its making real money taking a percentage of each payment processed through its app and its growing quickly through rapid worldwide expansion. Earlier this year, one of the company's investors, Bill Gurley of Benchmark Capital, said Uber is "probably the…fastest-growing company we've ever worked with." It's rumored to be seeking funding at a possible valuation of $1 billion. And it already operates in more than 30 cities around the world including Mexico City and Stockholm (both referenced above). 

This vast network could become a formidable competitive advantage for Uber, just by virtue of its global existence. If you downloaded the Uber app on your last trip to San Diego, why go to the trouble of even getting acquainted with an alternative in Hong Kong?

The Cab-Hailing Competitive Landscape

Despite its grwoth, Uber is far from alone in elbowing into the global urban taxi-and-limousine-transit space, which is an $11 billion industry just in the United States. Probably dozens of start-ups are moving into this formerly-staid industry are also largely like Uber--cab-hailing smart-phone apps that let drivers locate passengers, and passengers electronically hail drivers. Though the business models vary, they usually make money by collecting a small fee per "e-hail." While they're all taking a bite out of the urban transit space, they don't own vehicles or directy employ drivers. They're technology companies more than anything else. To nod to venture capitalist Marc Andreessen's frequent phrasing, this is software "eating" urban transportation.

Hailo, another cab-hailing app, operates in 10 cities including Boston, Chicago, Toronto, Barcelona, Madrid, and Tokyo, and is launching in Washington this month. It started in London, where its co-founder and CEO, Jay Bregman, had previously founded a same-day-delivery logistics company called eCourier. Still very popular in London, it has also amassed a significant ridership (and drivership) in Dublin. Other cab hailing companies include Flywheel, which is already in two cities and has eight in beta; Taxi Magic, which is in 45 cities, primilarily in the U.S.; and Get Taxi, in six cities from Moscow to Tel Aviv. There are also peer-to-peer ride-sharing companies, such as Lyft and Sidecar, which each are based in San Francisco and have services elsewhere as well.

Still, Uber is the closest to being truly global, with expansion in Asia, Australia, and Europe in addition to lots of cities in North America. The question seems: If it builds a large enough footprint in enough cities and regions, will it edge out competitors in any one? 

As of yet, there's really no such thing yet as market dominance in the worldwide urban-ground-transportation space. In the broad scope of urban logistics, the competition is fragmented, and a lot broader for each of the companies in or around this space than any of the CEOs of these ride-hailing/sharing/finding apps might like to admit. If a yellow cab is competition for Uber, is, say, the New York City subway?

According to research on the limousine and ground transportation industry by research firm IBISWorld, there are no dominant players in the U.S. market. Certainly there are several limousine and sedan company that operate in multiple cities--including Carmel Car Service and Tristar Worldwide--but they're nowhere near global name recognition. It's looking likely, considering the fast rates the new tech-based car-hailing services are growing at (Uber, for instance, doubled in size each quarter last year), and their pervasiveness in certain cities (Hailo is used by more than half of all cabs in London and Dublin), that one of them could soon be among the biggest--if not the biggest--ground transit companies as measured by revenue in the world.

For a formidable global competitive advantage to take hold here, you'd need to see a car-hailing app be in place in just about every major city a business traveler might land in, and for its service to be identifiable and dependable across many locations to that traveler. Here's where that gets tricky. The company doesn't just have to operate, it also has to be among the couple of best options for getting around in that city--meaning, essentially, be near the top of the market in every city it operates in. 

Certainly, Uber has early traction. It's getting travelers to open up its app in multiple cities. But on price, its premium service is not among the most competitive two or three options in several cities. Cost-conscious and adventurous travelers to San Francisco (several of my friends fall into this category) use Uber occasionally in New York City, but toggle between Sidecar and Lyft, which are reliable--and cheaper--when in the Bay Area. And might not a traveler reserve a Zipcar when in Birmingham or a DriveNow one-way rental car when in Berlin?

And this doesn't account for market particularities; in a city like New York, where there are already so many taxis, the reason to e-hail a cab may be the novelty of doing so.

Expansion Strategy: Product vs. Place

Hailo's Bregman says the company is not taking a first-to-market approach to global operations. Instead, it's going deep in select cities. "Creating a global brand is of course a big part of what we're trying to do," he says. "We're not rushing in anywhere--instead, we're working for wide appeal in the top 10 cities in taxi use."  

Bregman says Hailo has seen something of a brand advantage emerge among its drivers and riders in both Dublin and London, but says business travelers aren't the primary market for Hailo, so a global network isn't so important for his brand. Instead, building a strong user base is the goal, because the vision is larger than just cab-hailing. "You create a platform for something greater than taxis, and that's something that an enormous global footprint can really help for," Bregman says.

Some of these companies--Uber included--are expanding into slightly different lines of business to, effectively, target any consumer who'd hail a vehicle, ever. Uber now has taxi-hailing services in many cities, and something called Uber X, which is after another segment: car services that aren't quite as nice as luxury sedans.

"If someone is going to be a 'low-cost Uber,'" Kalanick, Uber's CEO, told me, referring to competitors on price, "we're going to be low-cost Uber."

Flywheel, another ride-hailing app company that was formerly known as Cabulous, is currently bridging from taxi-hailing to working also with sedan drivers.

As these companies continue their rapid-growth trajectories, it's certainly fascinating to consider the future of the taxi and limousine industry. My feature in the July/August issue of Inc. magazine on Uber explores the topic in more depth.

But in the meantime, what signs of growth or competitive differentiation do you see for these sedan and e-haling companies? Which do you use--if any? Let us know in the comments below.